1. Field of the Invention
The invention relates to a refractory protective tube, and in particular a vitreous-silica tube, for the heat treatment of simiconductor components, wherein at one end of which, during the heat treatment, a treating or working gas is introduced. This end is constricted and is disposed opposite a closed end, closed except for a gas outlet.
2. Discussion of the Prior Art
Protective tubes of this type are on the market in the form of vitreous-silica tubes. (See pages 8 to 9 of Applicant's pamphlet Q-B 3/112, "Quarzglas fur die Halbleiter-Technik" [Vitreous silica for use in semiconductor engineering], issued in November, 1974.)
The unconstricted end of the vitreous-silica tube is constructed, in particular, as a conical ground joint which is closed by means of a mating ground cap provided with a relatively small vent hole through which there is but little back diffusion of ambient air because of the locally increased gas velocity during the heat treatment of semiconductor components. The action of the vent hole depends, of course, on the flow rate of the treating or working gas and is exerted only when a predetermined gas flow rate is reached or exceeded.
It is the object of the invention to provide a refractory protective tube, and in particular a vitreous-silica tube, for the heat treatment of semiconductor components which is adapted to be used with an internal pressure higher than the ambient atmospheric pressure on the tube and wherein the risk of back diffusion of ambient air into the protective tube is positively eliminated regardless of the flow rate of the treating or working gas.